The most common fuels utilized in automobiles and trucks in the United States and other nations of the world are gasoline and diesel fuel. These fuels are customarily dispensed directly into vehicle fuel tanks at service stations. A dispensing system usually includes an underground storage tank where fuel is stored in large volumes. By means of a pump extending into or communicating with the storage tank, fuel is pumped on demand to an aboveground dispensing unit. The typical dispensing unit includes one or more metering system each with a flexible hose and nozzle.
Solid contaminants, such as dirt, rust, and the like, have always been a problem when it occurs in vehicle fuel. In like manner, water has also been a constant problem in fuels. However, the problem with particular and water contaminants is much more serious at the present time than in the past because of the almost universal adoption of fuel injection systems for vehicle engines. Fuel injection systems are considerably more sensitive to particulate matter than prior carbureted fuel systems. While diesel engines have always employed fuel injectors, in recent years the use of fuel injectors for gasoline engines has become common.
For these reasons, distributors of gasoline and diesel fuels have in recent years given increased attention to the requirements of clean, particulate and water free fuel. It should be pointed out that water is a continuous problem in connection with fuel. Tanks, pipelines, and so forth in which fuel is stored and/or transported are subject to condensation. Condensation is difficult to prevent and therefore accumulation of some water in stored fuel is very common. Water from spill containment manholes at fill risers is also a source of fuel contamination. In order to combat the possibility of water and/or particulate contaminants from passing into a vehicle fuel tank, service stations have empolyed the use of small canister type filters in fuel dispensing units. These canister type filters are designed to absorb water passing therethrough and intercept contaminants. In order to prevent water from being dispensed with gasoline or diesel fuel, canister filters have been devised which include an internal valve arrangement which closes off when the filter has absorbed a predetermined amount of water. For reference to a filter which functions to shut off in the event of water comtamination, reference may be had to U.S. Pat. No. 4,482,011, issued Nov. 27, 1984, entitled "Fuel Containment Monitor With A Shoutoff Valve." The prior issued patent shows the use of a ball functioning as a valve which is moved to a closed position when the pressure drop across a filter element reaches a preselected level due to the absorption of water by the filter element. The ball moves against a seat to prevent further fuel flow through the filter.
An improved canister type filter for closing against fuel flow when a predetermined amount of water has been absorbed by the filter having a valve which, after having moved to the valve closed position, is retained in such position is disclosed in co-pending U.S. patent . Ser. No. 07/393,222 entitled "Fuel Filter With Positive Water Shutoff" filed Aug. 14, 1989 and issued as U.S. Pat. No. 4,959,141 on Sep. 25, 1990.
These water absorbing and flow terminating filter elements have been successful in achieving their intended results of closing against further fuel flow in the event of the absorption of predetermined amounts of water. However, the application of such filters has been limited since they have typically been employed as canister filters attached aboveground to fuel dispensing units, and such aboveground applications are potenially envoironmentally contaminating.
The present disclosure is directed to a liquid fuel dispensing system having means for preventing inadvertent water and particular contamination which overcomes the problems and limitations with the existing systems as used in service stations today. Particularly, the disclosure herein provides a fuel dispensing system including an underground sump arrangement for receiving a filtration vessel therein and in which the filtration vessel is of a size permitting the use of relatively large filter elemments. Larger filter elements require less frequent replacement, thus reducing the atmospheric and ground water contamination that occurs with more frequent replacement of small filter elements attached aboveground directly to fuel dispensing units. Further, the disclosure herein provides an overall system of fuel dispensing wherein the pump for pumping the fuel from an underground storage tank to a fuel dispensing unit and all required filtration to intercept particulate matter and water are achieved within a confined underground sump.
Further advantages and improvements of this disclosure will be apparent from the following description.